Hey Guys thanks ahead of time for anyone with any insight. I will give you the full rundown on this setup and the diagnostics that I have ran already. This vehicle is a vin K COMPLETELY stock setup. 21,000 Miles on brand new engine. From summer all the way through the cold winter except up to about 3 weeks ago I noticed my gas mileage drastically dropped from an average of 22 and highway 26 (on a good day) went down to around 16-MAX 18 average and highway. Right away I threw the Solus-Pro on and saw fuel trims were way negative. So of course I suspected my 3rd reman'd maf...Well it did help but only with V.E numbers came up to about 83%. Unplugged maf and numbers plummeted to -32LT. B1S1 is switching properly and will switch quickly when a vac leak is created or propane added. Also did injector pressure drops at 1pulse 50mpulse and 100mpulse and all dropped almost identical. Im sure it is time for a new set of injectors having 150k on the stock injectors but this doesn't seem to be my issue. Have KOEO 55ramp down to stead 44ish...with no drop in 10 minutes. No "external" regulator leaks and pulled rail to check for any injector leak down or excessive spray pattern. All checked out...changed the "filthy" fuel filter and did nothing besides let cleaner gas in -_- I have access to Terra Clean and BG system cleaners and these have all been done multiple times looking for injector issues. Car does seem to stumble with a slightly rough idle and misfire counters will show occasionally irregular misses but nothing will log. Have no vac leaks of any kind all air inlets are spotless. One thing I was not sure of was that I unplugged Maf and still had a reading of 1.88gsec which may be normal for the grand prix's but just to make sure i checked for any short to power/grounds on maf signal wires and power and ground wires and nothing. Few things i havent checked is vapor canister but there def is no fuel leaks and ive tried multiple gases but once I saw the fuel trims i ruled that far out, running compression (which I would hope is fine being a farely new motor) but i have no fumes or smoke from tails. Also has a brand new Magnaflow High flow stainless cat. So im running out of ideas and places to check....
